Improvements in the design of semiconductor devices consistently involve an increase in both operating frequency and capacity of such devices. In many cases, these improvements are made with little increase, if not a decrease, in the size of these devices. As a result, density of components, such as transistors, on each of these devices has greatly increased. However, advancements in this regard have not been without drawbacks. For example, as operating frequencies and capacities of semiconductor devices have increased, so has the amount of noise generated from the increases in transistor switching, a drawback that is been even more difficult to address as a result of decreases in signal margins associated with higher frequencies and lower power supply voltages.
An approach that has been used to reduce unwanted noise has been the use of decoupling capacitors. As a result, high-frequency signals may be filtered from power supply voltages provided to, and derived in, semiconductor devices.
Another example use of capacitors is to provide power backup. For instance, there may be latency associated with write operations to nonvolatile memory storage devices. As result, a queue may be utilized to temporarily store write commands and/or data until non-volatile memory commands can execute each command serially. Example implementation for such queue involves using a volatile memory buffer cache such that write data are written first to the volatile memory buffer cache and subsequently to solid-state memory when the solid-state memory is available. A problem which may occur is that data intended to be stored in a solid-state device may be lost if the device loses power while data is being written to the volatile memory. Capacitors may be used to provide backup power in the event of power failure, and specifically to provide sufficient backup power to enable data transfer from the buffer cache to nonvolatile memory.
Capacitors may additionally, or alternatively, serve numerous other purposes relative to integrated circuitry besides the purposes specifically described in the examples provided above.
In many applications it is desirable to provide capacitors separately from one or more integrated circuit chips. For instance, capacitors may be provided on a capacitive chip within a multi-chip module; with a “capacitive chip” being a chip for which a substantial purpose is to provide one or more capacitors. There is a continuing goal to reduce costs and improve capacitors associated with capacitive chips.